Separate (9x^2 + 8x + 10)/(x^2 + 1)(x + 2) into partial fractions.

First, we find the form of the two fractions we're going to get. As one denominator has a power of 2, and the other a power of 1, our answer will be of the form: [(Ax+B)/(x2+1)] + [C/(x+2)]. If we make this our Right Hand Side, and make the question's equation our Left Hand Side, and then multiply by our LHS denominator, we get 9x2+8x+10=(Ax+B)(x+2)+C(x2+1). If we then set x = -2, to eliminate our Ax+B term, so that we can solve for C, our equation becomes 9(-2)2+8(-2)+10=C[(-2)2+1], Simplifying, we get 30=5C, and solve C=6. We then put this back into the initial equation we made and move the C fraction to the other side, we get (Ax+B)/(x2+1) = [(9x2+8x+10)/(x+2)(x2+1)] - [6/(x+2)]. We then make our RHS into one single fraction, by multiplying the latter fraction, top and bottom, by (x2+1). If we then simplify the numerator of our new RHS, we get (3x2+8x+4)/(x+2)(x2+1). We can factorise the numerator to give us (3x+2)(x+2), and find that the x+2 cancels out with the denominator. Now, our whole equation becomes (Ax+B)/(x2+1) = (3x+2)/(x2+1). Equating our coefficients of x, we find that A = 3, B = 2. So, our final solution is: (9x2+8x+10)/(x+2)(x2+1) = [(3x+2)/(x2+1)] + [6/(x+2)].

LU

Related Maths A Level answers

All answers ▸

How do I solve equations with modulus functions on both sides?


Show that sqrt(27) + sqrt(192) = a*sqrt(b), where a and b are prime numbers to be determined


There is a Ferris wheel where the passengers are placed 10m away from the centre. At what speed must they be moving in order for them to feel completely weightless at the top of the wheel.


Find the equation of the tangent to the curve y = 2 ln(2e - x) at the point on the curve where x = e.